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Peerless fans... inverted dust caps; imaging?

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  • Peerless fans... inverted dust caps; imaging?


    Just curious what others think of the effects on imaging regarding Peerless midwoofers' inverted dust caps. Just happened to notice while cleaning, they seems to be a different material than first thought... not as hard/thick as they first appeared. I remember hearing about inverted caps years ago, but not really what the talk was... does anyone think this particular design has a lesser or greater effect on imaging than the usual/norm?

    Thanks, GC

  • #2
    Re: Peerless fans... inverted dust caps; imaging?


    Variations in dust cap materials and design are going to have more of an effect on upper end driver response. I suspect any changes in imaging will not be particularly significant, and dependant on the passband utilized.

    C

    Curt's Speaker Design Works

    "It is the mark of an educated mind to be able to entertain a thought without accepting it."
    - Aristotle

    Comment


    • #3
      Re: Peerless fans... inverted dust caps; imaging?


      > Variations in dust cap materials and design
      > are going to have more of an effect on upper
      > end driver response. I suspect any changes
      > in imaging will not be particularly
      > significant, and dependant on the passband
      > utilized.

      > C

      I thought I read once that there is a formula to determine what % of the cone is actually being utilized to reproduce sound...
      It had something to do with the diameter . freq.

      In any event, I believe that you can totally dent a convex dust cap on a woofer in a traditional 2-way or 3-way and not effect the sound in any significant way. Maybe, a person could hear the difference on a very small 2-way (using a 4" woofer or something), but I doubt it.

      I think manufacturers went to an inverted style firstly for aesthetic reasons and secondly for structural reasons ie. continuing the parabolic shape of the cone. Supposedly to reduce harmonic influences from the changing cone shape at the dust-cap attachment point.

      Peerless makes some very nice drivers, esp. for the money, I like to think they know what they are doing...

      Don't listen to me - I have not sold any $150,000 speakers.

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      • #4
        Curt's Speaker Design Works

        "It is the mark of an educated mind to be able to entertain a thought without accepting it."
        - Aristotle

        Comment


        • #5

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          • #6
            11 bucks?


            which one?

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            • #7
              Morel 5.2


              Morel mentions that the inverted cloth dustcap in this model 'improves midrange performance'. Very lightweight cone as well - I think around 5 gms.; has made me think about this driver as a midrange in a 3 way..

              Comment


              • #8
                Re: Peerless fans... inverted dust caps; imaging?

                Sorry to bring this back, but got to thinking about dust caps again... just bought a pair of Peerless 830657 6.5" midwoofers, and they have the inverted caps. I also have several Peerless 5.25" (Snell & Dali) midwoofers, and they also have the inverted caps. Seems this plays a positive role in the upper midrange/lower treble, especially paper caps.

                Any thoughts??

                GC

                Comment


                • #9
                  Re: Peerless fans... inverted dust caps; imaging?

                  Originally posted by gc1 View Post
                  Just curious what others think of the effects on imaging regarding Peerless midwoofers' inverted dust caps. Just happened to notice while cleaning, they seems to be a different material than first thought... not as hard/thick as they first appeared. I remember hearing about inverted caps years ago, but not really what the talk was... does anyone think this particular design has a lesser or greater effect on imaging than the usual/norm?

                  Thanks, GC
                  I doubt it would be significant, but the only way to know for sure would be to do a before and after comparison with and without the dustcap On/Off/Inverted etc.

                  Most dustcaps don't contribute very much to the total radiating area.
                  Quit looking at the dust caps and listen for the imaging if you get a chance to audition the woofers.

                  Comment


                  • #10
                    Re: Peerless fans... inverted dust caps; imaging?

                    Yeah, but those "higher frequencies" are probably already handled by the crossover and likely will never reach the woofer to begin with.
                    The best dust cap would be no dust cap at all, except of course you need to keep the dust out!
                    I've often wondered why they just don't fabricate whole homogeneous cones without an opening (hole) at the apex! Then there would be no need to glue on a separate dustcap.
                    The hole in the cone is really only there to facilitate gluing, assembly. Putting together the cone and voice coil and then aligning it all in the gap/pole piece.

                    Originally posted by curt_c View Post
                    At higher frequencies, a significant amount of the driver response may radiate from the dust cap, depending on the damping of the cone. The dust cap porosity, stiffness, density, and shape all affect the response of the driver. Also there will be a resonant cavity created behind the dust cap and in front of the pole piece. This resonant frequency will also affect the driver response and will be dependent on the volume of the cavity, venting, etc.

                    An inverted poly dust cap will generally provide a smoother response roll off than a convex one, and designed properly, can further strengthen the junction of the former and cone area.

                    Personally, I like the look of the inverted dust cap better. -Also, its one less ‘button’ for the wee ones to be tempted to push.

                    C
                    Last edited by ; 03-08-2009, 03:15 AM.

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                    • #11
                      Re: Peerless fans... inverted dust caps; imaging?

                      ...I've often wondered why they just don't fabricate whole homogeneous cones without an opening hole) at the apex! Then there would be no need to glue on a separate dustcap...
                      Vifa fiberglass and wood pulp cone woofers XG18 models, I think?

                      I like the Peerless Nomex woofers better than the HDS Nomex with the phase plugs, based on the FR at least.
                      "...this is not a subwoofer" - Jeff Bagby ;)

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                      • #12
                        Re: Peerless fans... inverted dust caps; imaging?

                        Originally posted by critofur View Post
                        Vifa fiberglass and wood pulp cone woofers XG18 models, I think?

                        I like the Peerless Nomex woofers better than the HDS Nomex with the phase plugs, based on the FR at least.
                        I have a pair of the older Nomex... beautiful sound (especially for the money)!!

                        GC

                        Comment


                        • #13
                          Re: Peerless fans... inverted dust caps; imaging?

                          Yeah, but those "higher frequencies" are probably already handled by the crossover and likely will never reach the woofer to begin with.
                          The best dust cap would be no dust cap at all, except of course you need to keep the dust out!
                          I've often wondered why they just don't fabricate whole homogeneous cones without an opening hole) at the apex! Then there would be no need to glue on a separate dustcap.
                          The hole in the cone is really only there to facilitate gluing, assembly. Putting together the cone and voice coil and then aligning it all in the gap/pole piece.
                          Phase plugs make the most sense to me. No cavity resonance under the dust cap, lower Le and distortion, better cooling and off axis response.

                          C
                          Curt's Speaker Design Works

                          "It is the mark of an educated mind to be able to entertain a thought without accepting it."
                          - Aristotle

                          Comment

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